This invention relates to a zero-crossing circuit and, in particular, to a zero-crossing circuit which is particularly adapted for reading information recorded on a magnetic disk or tape.
When informaton is read from a magnetic disk, tape or similar magnetic surface storage element, the magnetic head reading the information provides analog voltage signals which may indicate the data being read by crossing a zero voltage or other reference. A zero-crossing circuit is thus used to receive the output of the magnetic head and indicate the data. Such zero-crossing circuits often contain threshold circuits which provide signals when the input signal goes above or below predetermined voltage thresholds. Consequently, hysteresis within the threshold circuits, differences between the turn-off and turn-on voltage thresholds, can cause errors in reading the data.